1. Technical Field
Novel photoresist monomers, polymers thereof and photoresist compositions containing the same are disclosed. In particular, photoresist monomers suitable for a photolithography process using DUV (deep ultraviolet) light sources, particularly VUV (vacuum ultraviolet: 157 nm) in fabricating minute circuits for highly integrated semiconductor devices, photoresist polymers thereof and photoresist compositions containing the same, and preparation processes are also disclosed.
2. Description of the Related Art
In general, a useful photoresist for ArF and VUV has a variety of desired characteristics, such as low light absorbance at the wavelength of 193 nm and 157 nm, excellent etching resistance, and excellent adhesiveness to a wafer. In addition, a photoresist should be easily developable in a commercially readily available developing solution, such as 2.38 wt % and 2.6 wt % aqueous tetramethylammonium hydroxide (TMAH) solution.
Recently, much research has been conducted on resins having a high transparency at the wavelength of 248 nm and 193 nm and dry etching resistance similar to novolac resin. However, most of these photoresists are not suitable for VUV due to their poor transmittance at 157 nm wavelength.
In order to solve the problem, research on polyethylene or polyacrylate containing fluorine has been performed. As an example, a tetrafluoroethylene as a monomer has been studied by DuPont. Tetrafluoroethylene is difficult to control and handle effectively when it is polymerized with other comonomers since it exists in gaseous phase. Therefore it yields inconsistent rates of polymerization.